Abstract

A silicon (840) channel‐cut crystal with a large asymmetry is used to linearly polarize synchrotron radiation generated by an undulator source at the 14.413 keV nuclear resonance of 57Fe. The resulting σ̂‐polarized radiation is then scattered from an 57Fe foil placed in a magnetic field that effects σ̂→π̂ polarization conversion within the resonant bandwidth. A second crystal of the same type is placed in a crossed position to suppress the nonresonant radiation while transmitting the π̂‐polarized resonantradiation. A polarization suppression factor of 6×10−7 has been obtained. The suppression of the nonresonant radiation allowed monitoring the decay of the nuclear levels after 1 ns of their excitation.